Apparatus for transmitting rotational power to a roll

ABSTRACT

Rotational power is transmitted to a roll of the type having a cylindrical, hollow shell rotatably mounted on a stationary, central through-shaft by a gear system composed of an internally spur gear affixed to the shell, a pair of pinion gears mounted for rotation by self-aligning bearings carried on shafts affixed to the through-shaft of the roll and an external spur gear positioned within a cavity in the main shaft. The pinion gears partially project through openings formed in walls that define a cavity in the shaft, and the axis of each pinion gear shaft is oriented parallel to the shell of the roll in a plane that is perpendicular to the plane along which the shell and shaft will deflect when loaded. The external spur gear is connected to a drive shaft that is composed of two portions connected to each other by a universal coupling, the portion of the drive shaft carrying the external spur gear thus being mounted for articulation relative to the main power input shaft. The elements of the gear system are maintained in parallel relation to each other and in proper mesh, regardless of the extent of deflection of the shell and through-shaft of the roll under load.

United States Patent 11 3,678,775 Danielsson July 25, 1972 [54]APPARATUS FOR TRANSIVIITTING Primary Examiner-Leonard H. GerinROTATIONAL POWER TO A ROLL [72] Inventor: Erik Danielsson, Karlstad,Sweden [73] Assignee: Aktiebolaget Karlstad Mekaniska Werkstad,Karlstad, Sweden [221' Filed: Oct. 20, 1970 [21] Appl. No.: 82,447

[30] Foreign Application Priority Data Oct. 21, I969 Sweden .14406/69[52] U.S. Cl ..74/4l0 [51] Int.Cl ....Fl6h 57/00 [58] Field of Search..74/4l0, 665 P [56] References Cited UNITED STATES PATENTS 2,936,6555/1960 Peterson et al. ..74/410 X 3,451,290 6/1969 Wildhaber ...74/4l0 X3,572,171 3/1971 Per-Erik Arne Larsson ..74/4l0 Attorney-Brumbaugh,Graves, Donolhue & Raymond [5 7] ABSTRACT Rotational power istransmitted to a roll cylindrical. hollow shell rotatably mounted on astationary, central through-shaft by a gear system composed of aninternally spur gear affixed to the shell, a pair of pinion gearsmounted for rotation by self-aligning bearings carried on shafts affixedto the through-shaft of the roll and an external spur gear positionedwithin a cavity in the main shaft. The pinion gears partially projectthrough openings formed in walls that define a cavity in the shaft. andthe axis of each pinion gear shaft is oriented parallel to the shellofthe roll in a plane that is perpendicular to the plane along which theshell and shaft will deflect when loaded. The external spur gear isconnected to a drive shaft that is composed of two portions connected toeach other by a universal coupling, the portion of the drive shaftcarrying the external spur gear thus being mounted for articulationrelative to the main power input shaft. The elements of the gear systemare maintained in parallel relation to each other and in proper mesh,regardless of the extent of deflection of the shell and through-shaft ofthe roll under load.

of the type having a 3 Claims, 3 Drawing Figures =44 5:7 VIII/I PatentedJuly 25, 1972 3,678,775

2 Sheets-Sheet 1 INVENTOR. ERIK DANIELSSON (L ;Z r

his ATTORNEYS Patented July 25, 1972 3,678,775

2 Sheets-Sheet 2 INV EN TOR.

3 BY ERIK D1822 his ATTORNEYS APPARATUS FOR TRANSMITTING ROTATIONALPOWER TO A ROLL BACKGROUND OF THE INVENTION This invention relates torolls of the type comprising a hollow, cylindrical shell that isrotatably mounted on a stationary central through-shaft and, inparticular, to apparatus for transmitting rotational power to the shellof the roll.

In a common form of the construction for rotatable rolls that aresubjected to high loading and are required to present a true surface ata nip with another roll, such as calender rolls used for calenderingpaper and paperboard and other sheettype products, a hollow, cylindricalshell is mounted for rotation about a fixed, central through-shaft thatis suitably supported at each end, and in turn supports the shell bymeans of bearings adjacent the ends of the shell. Frequently, theserolls include mechanisms for compensating for the deflection anddeformation of the shell and shaft under the dead load of the rollitself and the loads which are imposed upon it in operation. Thedeformation and deflection of the shell on the one hand and the shaft onthe other hand almost always result in the shaft axis and roll axisbeing non-parallel over most of the length of the roll, and the lack ofparallel relation of the axes makes it difficult to provide for thetransmission of rotary power to the shell. Various types of rotarydrives for these types of rolls have been proposed and used in the past.

For example, one type of drive is composed of either an internal orexternal gear ring affixed to one end of the tubular shell of the rolland driven by a gear carried on a drive shaft that is positionedparallel to the shell and adjacent the through-shaft of the roll. Asignificant disadvantage of this arrangement is that it requires aconsiderable amount of space in the region adjacent the roll ends andthe roll supports, such space often being required for other equipmentassociated with the roll.

Another type of drive employs a three-ring bearing for mounting theshell. The inner ring of the bearing is mounted on the end of the shaftof the roll, the outer ring is mounted in a bearing support that is partof the support for the main shaft of the roll, and the center ring ofthe three is attached on one side to the shell and on the other side toa rotatable drive shaft that is coaxial with the shell and extends tothe outside of the support for the roll. With such an arrangement, halfof the total of the dead load and the operating load are transmitted toone of the supports of the roll through the three-ring bearing. If thebearing is to have a reasonable service life, it must have a relativelylarge outside diameter which, in most cases, will be impracticablylarge, relative to the diameter of the roll. Accordingly, the onlypractical solution is to sacrifice service life in order that thehearing may be of a practical size.

SUMMARY OF THE INVENTION There is provided, in accordance with thepresent invention, a novel and an improved apparatus for transmittingrotational power to a roll of the type composed of a shell rotatablymounted on a fixed through-shaft. The apparatus comprises a gear systemfor transmitting driving force to the shell by way of a drive shaft thatis generally coaxial with the through-shaft of the roll. The componentsof the gear system are, according to the invention, mounted in such away as to remain in proper mesh and in proper alignment and, therefore,are not subject to extraordinary wear due to improper mesh.

More particularly, an internal spur gear of the gear system is affixedto the shell adjacent one end of the roll and in coaxial relation to theshell. A pair of pinion gears are mounted in positions opposite eachother for rotation by means of selfaligning bearings carried on shaftsthat are affixed to the through-shaft of the roll. The pinion gears are,of course, positioned to mesh with the internal spur gear, and the axisof each pinion gear shaft is oriented parallel to the shell in a planethat is perpendicular to the plane along which the shell and shaft walldeflect and deform when loaded in normal operation of the roll. Anexternal spur gear in the gear system is positioned within a cavityformed in the end of the shaft and having openings through which thepinion gears partially project in order to mesh with the external spurgear.

In the usual form of construction embodied in rolls of the type withwhich the invention is concerned, the shell is mounted on thethrough-shaft by means of self-aligning bearings of the type having aspherical outer race that allows the bearing balls or rolls to run true,even though the axis of the shell may not be aligned with the axis ofthe roll under the loaded condition. When the shell is loaded inoperation, the load is transmitted from the shell to the shaft andcauses the shaft to bow. Various known mechanisms are frequentlyemployed to keep the shell surface straight or true or even to cause itto bend in a direction opposite to that of the shaft. With suchmechanisms, the axes of the shell and the shaft will be non-parallel toeach other along almost the entire length of the roll. Preferably, adrive arrangement, according to the invention, embodies, as a furtherfeature to compensate for the lack of alignment between the shell andshaft axes, the use of a universal coupling in the shaft on which theexternal spur gear of the gear system is mounted and by which the shellis driven. More particularly, the drive shah includes two portions, theoutermost portion of which, relative to the longitudinal center of theroll, is mounted for rotation on an axis that is coaxial with the end ofthe through-shaft of the roll. The second portion is connected to thefirst by a suitable universal coupling at one end and carries theexternal spur gear at the other end.

Consequently, the external spur gear can shift position, relative to thepinion gears, so as to afford a proper mesh with the external spurgears.

Among the advantages of the drive arrangement, according to theinvention, is the fact that it occupies a minimum of space and, inparticular, is based on components that are mounted substantiallyentirely within the elements of the roll shell and the through-shaftrather than outside of the shaft, as in the form of drives employedheretofore. The drive arrangement does not require providing relativelycomplicated sup port arrangements for the through-shaft and for thebearings of the shell, nor does it require designing and dimensioningthe supports, shaft and bearings so that they are adapted to performfunctions other than their primary purposes. Further, none of thecomponents of the gear system are employed to support any components ofthe roll, as is the case with some types of drive. If a drivearrangement, according to the invention, embodies the preferred featureof mounting the external spur gear on a shaft portion that canarticulate relative to the main drive shaft, the further advantage ofthe maintenance of a proper mesh between the external spur gear, thepinion gears and the internal spur gear, due to the self-aligningtendency of the gears, contributes significantly to the useful life ofthe drive arrangement.

DESCRIPTION OF THE DRAWINGS For better understanding of the inventionand the advantages it provides, reference may be made to the followingdescription of an exemplary embodiment, taken in conjunction with thefigures of the accompanying drawings, in which:

FIG. 1 is a cross-sectional view taken generally along the axis of theroll and along a plane that is substantially perpendicular to the planealong which the roll will deform and deflect upon loading, the viewillustrating only the end portion of the roll and the components of thedrive arrangement;

FIG. 2 is a cross-sectional view taken generally along the axis of theroll and in a plane perpendicular to the plane of the section of FIG. 1,the view further illustrating the components in positions into whichthey shift upon loading of the roll, but to a greatly exaggeratedextent; and

FIG. 3 is a cross-sectional view taken along a plane substantiallyperpendicular to the axis of the roll at the location of the gearsystem, as represented generally by the lines 3-3 in FIG. 2, and alsoshowing the components in shifted positions under loading.

In the drawing, the reference numeral 1 designates generally the shellof the roll, the shell 1 being rotatably journaled by means ofself-aligning bearings 3 on a stationary central through-shaft 5. Theshaft 5 is supported at each end by a swivel mounting 7, only one ofwhich is illustrated in the drawing. The end of the shaft which is toincorporate the drive that rotates the shell on the shaft, i.e., the endof the roll that is illustrated in the drawing, is formed with a hollowcavity 9, and a drive shaft, which is designated generally by referencenumeral 11, extends longitudinally into the cavity 9. The shaft carriesan external spur gear 13 which is affixed to the shaft and forms a partof a gear system that is employed to drive the shell 1. The externalspur gear meshes with a pair of pinion gears 15 and 17 which, in turn,mesh with an internal spur gear 19 that is affixed to the shell 1. Thepinion gears 15 and 17 extend partway into the cavity through slots 21and 23 (see FIG. 3) formed in the wall that defines the cavity 9. Thepinion gears 15 and 17 are mounted for rotation by means of selfaligningbearings 25 and 27 on shafts 29 and 31 that are atfixed to a pinion gearcarrier in the form of a ring 33 that is affix'ed to the through-shaft5. The drive shaft 11 is composed of a portion 41 that is supported onan axis that is coaxial with the shaft 5 by a pair of spaced-apartbearings 37 and 39 appropriately mounted within the cavity, and aportion 42 that is connected to the portion 41 by a universal coupling35. The main portion 41 of the drive shaft 1 1 is connected to a sourceof power (not shown).

The manner by .which the gear system maintains itself in proper mesh isdescribed below, and reference should be made to FIGS. 2 and 3 inconjunction with the description.

When the roll is subjected to a load, the load is transmitted throughthe self-aligning bearing 3 to the through-shaft 5, which in turntransmits the load into the swivel mounting 7. Because of thetransmission of the load from the shell to the shaft through bearingsthat are located in spaced relation to the mounting 7 for the shaft, theshaft will be deformed or bowed by the loading. If the roll is a typethat is provided with devices between the shell 1 and the shaft 5 forcounteracting the bending, for example, devices which provide hydraulicpressure on the inner side of the shell in a direction against the load,a portion of the load will be transmitted through these devices to thecentral shaft. By means of such devices, the shell may be maintainedstraight or even be caused to bend in a direction opposite to that ofthe shaft.

FIGS. 2 and 3 of the drawings illustrate the locations and directions ofthe axes of various elements of the roll and drive when they aredeflected under load, the degree of deflection being exaggerated forgreater clarity of illustration. In FIG. 2, the reference number 51designates the axis of the throughshaft 5, 57 designates the axis of theexternal spur gear 15, 59 and 61 designate the axes of the two piniongears 15 and 17, 63 designates the axis of the internal spur gear 19 and67 designates the axis of the main portion 41 of the drive shaft 1 1.

When the roll is not subjected to any load, the axes 51 and 63 of theshell 1 and the through-shaft 5 of the roll, the axis of rotation 57 ofthe external spur gear 13, the axes of rotation 59 and 61 of the piniongears 15 and 17, the axes of rotation 63 of the internal spur gear 19,the axis of rotation 67 of the shaftportion 41, the fulcrum of 65 of theuniversal coupling 35 and center of rotation 55 of the bearing 3 bywhich the shell 1 is mounted on the through-shaft 5 are all located in acommon plane which is perpendicular to the direction of the load towhich roll will be subjected.

Because of the bowing of the through-shaft 5 under the load transmittedto it from the shell 1, its axis 53, at the longitudinal central planeof the bearing 3, is at an angle to the axis 51 of the shell 1 at thesame plane. Moreover, the axes 51 and 53 coincide only at a point 55which constitutes the center of the spherical surface of theself-aligning bearing 3. Outside the self-aligning bearing 3, that is,to the right on FIG. 2, the axis 51 of the shell and the axis 63 of theinternal spur gear 19 are below the axis of that part of the shaft 5that is to the right of the bearing 3, such part also being the part ofthe shaft on which the pinion gear carrier 33 is mounted. Accordingly,the

axes 59 and 61 of the pinion gears 19 are located above the axis 51 ofthe shell 1 and the axis 63 of the internal spur gear 19 (see FIG. 3).

In order for the gear system to function properly without undue strainand possible failure and under conditions that limit wear of the gear asmuch as possible, it is necessary that the axes of rotation 59 and 61 ofthe pinion gears 15 and 17, the axis of rotation 57 of the external spurgear 13 and the axis of the rotation 63 of the internal spur gear 19remain parallel at all times. The drive arrangement, according to theinvention, meets that requirement in the following manner.

To begin with, the axis of rotation 63 of the internal spur gear 19coincides with the axis 51 of the shell 1 of the roll, since theinternal spur gear 19 is mounted on the shell. Inasmuch as the piniongears 15 and 17 are, as mentioned above, joumaled on self-aligningbearings 25 and 27, they are able to pivot so that their axes ofrotation will remain parallel to the axis of rotation of the internalspur gear 19, such pivoting of the pinion gears resulting from thetendency for the pinion gears to want to track properly on the internalspur gear. Inasmuch as the external spur gear 13 is mounted on a shaftportion 42 that is articulated on a fulcrum, which is designated by thenumeral 65 in FIG. 2, constituted by the center of the universalcoupling 35, it can shift in response to adjustment of the position ofthe pinion gears so that its axis of rotation 57 will be parallel to theaxis of rotation 63 of the internal spur gear 19.

As described above, whenthe shell 1 is subjected to a load in operationand, therefore, is displaced downwardly upon bending of thethrough-shaft 5, the internal spur gear 19 is likewise displaceddownwardly relative to the pinion gears 15 and 17. Such displacementcauses the pinion gears 15 and 17 to rotate slightly on their bearings,the pinion gear 15 rotating counterclockwise and the pinion gear 17rotating clockwise. It is these rotations of the pinion gears that causethe external spur gear 13 to be displaced upwardly, the amount of upwarddisplacement of the external spur gear 13 relative to the planet gears15 and 17 being equal to the amount of displacement downwardly of theinternal spur gear 19 relative to the pinion gears. As mentionedpreviously, the pinion gears are free to shift so that their axes remainparallel to the axis of the internal spur gear 19, and they will all doso in order to track properly on the internal spur gear.

Preferably, the universal coupling 35 in the shaft 11 is located,longitudinally of the roll, so that it is equidistant from thelongitudinal center 69 of the external spur gear 13 and the longitudinalcenter of the bearing 3. With this relationship, which createssubstantially equilateral triangles between portions of the axesinternecting at the points 55 and 65, the axis of rotation 57 of theexternal spur gear 13 will always remain substantially parallel to theaxis of rotation of the internal spur gear, regardless of the extent ofrelative displacement of the axis of the internal spur gear relative tothe axis of the through-shaft.

Thus there is provided, in accordance with the invention, a drivearrangement in which all of the gears of the gear system remain parallelunder various conditions of operation. Although the manner in which thegear system achieves parallel relation between the axes of thecomponents also results in slight relative displacements of the axes ofthe components in transverse planes of the roll, such relativedisplacements are of insignificant magnitude. The slight relativedisplacements of the gears in the axial direction of the roll are alsoinsignificant and do not affect the operation of the gear train,particularly if the teeth of the gears are straight.

I claim:

1. Apparatus for transmitting rotational power to a roll of the typehaving a cylindrical shell rotatably mounted by selfaligning bearings ona stationary central shaft that is supported at each end comprising aninternal spur gear afiixed to the shell and coaxial therewith, a pair ofpinion gears mounted for rotation by self-aligning bearings carried onshafts afl'ixed to the central shafi of the roll, the pinion gears beingpositioned to mesh with the internal spur gear and the axis of eachpinion gear shaft being oriented parallel to the shell in a plane thatis perpendicular to the plane along which the shell and shaft willdeflect when loaded, and a driven external spur gear positioned within acavity in the shaft and meshing with the pinion gears, the pinion gearspartially projecting through openings in the walls of the central shaftthat define the cavity, and the external spur gear, pinion gears andinternal spur gear constituting a gear system for transmission ofdriving power to the shell to rotate it about the central shaft.

2. Apparatus according to claim 1 and further comprising a first driveshaft component carrying the extema] spur gear, a second drive shaftcomponent mounted for rotation about an axis substantially coincidentwith the axis of the central shalt of the roll, and a universal couplingbetween the drive shaft components to afford articulation between thedrive shaft components while transmitting rotation between them.

3. Apparatus according to claim 2 wherein the distances, measuredaxially of the roll, (1) from the axial center of the bearings by whichthe shell is mounted on the shaft to the axial center of the externalspur gear and (2) from the axial center of the external spur gear to thefulcrum of the universal coupling are substantially equal.

I! I l l i

1. Apparatus for transmitting rotational power to a roll of the typehaving a cylindrical shell rotatably mounted by selfaligning bearings ona stationary central shaft that is supported at each end comprising aninternal spur gear affixed to the shell and coaxial therewith, a pair ofpinion gears mounted for rotation by self-aligning bearings carried onshafts affixed to the central shaft of the roll, the pinion gears beingpositioned to mesh with the internal spur gear and the axis of eachpinion gear shaft being oriented parallel to the shell in a plane thatis perpendicular to the plane along which the shell and shaft willdeflect when loaded, and a driven external spur gear positioned within acavity in the shaft and meshing with the pinion gears, the pinion gearspartially projecting through openings in the walls of the central shaftthat define the cavity, and the external spur gear, pinion gears andinternal spur gear constituting a gear system for transmission ofdriving power to the shell to rotate it about the central shaft. 2.Apparatus according to claim 1 and further comprising a first driveshaft component carrying the external spur gear, a second drive shaftcomponent mounted for rotation about an axis substantially coincidentwith the axis of the central shaft of the roll, and a universal couplingbetween the drive shaft components to afford articulation between thedrive shaft components while transmitting rotation between them. 3.ApparatUs according to claim 2 wherein the distances, measured axiallyof the roll, (1) from the axial center of the bearings by which theshell is mounted on the shaft to the axial center of the external spurgear and (2) from the axial center of the external spur gear to thefulcrum of the universal coupling are substantially equal.